/*
 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
 *
 */
package javax.sql.rowset.serial;

import java.sql.*;
import java.util.Arrays;
import java.util.Map;
import sun.reflect.misc.ReflectUtil;

/**
 * An input stream used for custom mapping user-defined types (UDTs).
 * An <code>SQLInputImpl</code> object is an input stream that contains a
 * stream of values that are the attributes of a UDT.
 * <p>
 * This class is used by the driver behind the scenes when the method
 * <code>getObject</code> is called on an SQL structured or distinct type
 * that has a custom mapping; a programmer never invokes
 * <code>SQLInputImpl</code> methods directly. They are provided here as a
 * convenience for those who write <code>RowSet</code> implementations.
 * <P>
 * The <code>SQLInputImpl</code> class provides a set of
 * reader methods analogous to the <code>ResultSet</code> getter
 * methods.  These methods make it possible to read the values in an
 * <code>SQLInputImpl</code> object.
 * <P>
 * The method <code>wasNull</code> is used to determine whether the
 * the last value read was SQL <code>NULL</code>.
 * <P>When the method <code>getObject</code> is called with an
 * object of a class implementing the interface <code>SQLData</code>,
 * the JDBC driver calls the method <code>SQLData.getSQLType</code>
 * to determine the SQL type of the UDT being custom mapped. The driver
 * creates an instance of <code>SQLInputImpl</code>, populating it with the
 * attributes of the UDT.  The driver then passes the input
 * stream to the method <code>SQLData.readSQL</code>, which in turn
 * calls the <code>SQLInputImpl</code> reader methods
 * to read the attributes from the input stream.
 *
 * @see java.sql.SQLData
 * @since 1.5
 */
public class SQLInputImpl implements SQLInput {

  /**
   * <code>true</code> if the last value returned was <code>SQL NULL</code>;
   * <code>false</code> otherwise.
   */
  private boolean lastValueWasNull;

  /**
   * The current index into the array of SQL structured type attributes
   * that will be read from this <code>SQLInputImpl</code> object and
   * mapped to the fields of a class in the Java programming language.
   */
  private int idx;

  /**
   * The array of attributes to be read from this stream.  The order
   * of the attributes is the same as the order in which they were
   * listed in the SQL definition of the UDT.
   */
  private Object attrib[];

  /**
   * The type map to use when the method <code>readObject</code>
   * is invoked. This is a <code>java.util.Map</code> object in which
   * there may be zero or more entries.  Each entry consists of the
   * fully qualified name of a UDT (the value to be mapped) and the
   * <code>Class</code> object for a class that implements
   * <code>SQLData</code> (the Java class that defines how the UDT
   * will be mapped).
   */
  private Map<String, Class<?>> map;


  /**
   * Creates an <code>SQLInputImpl</code> object initialized with the
   * given array of attributes and the given type map. If any of the
   * attributes is a UDT whose name is in an entry in the type map,
   * the attribute will be mapped according to the corresponding
   * <code>SQLData</code> implementation.
   *
   * @param attributes an array of <code>Object</code> instances in which each element is an
   * attribute of a UDT. The order of the attributes in the array is the same order in which the
   * attributes were defined in the UDT definition.
   * @param map a <code>java.util.Map</code> object containing zero or more entries, with each entry
   * consisting of 1) a <code>String</code> giving the fully qualified name of the UDT and 2) the
   * <code>Class</code> object for the <code>SQLData</code> implementation that defines how the UDT
   * is to be mapped
   * @throws SQLException if the <code>attributes</code> or the <code>map</code> is a
   * <code>null</code> value
   */

  public SQLInputImpl(Object[] attributes, Map<String, Class<?>> map)
      throws SQLException {
    if ((attributes == null) || (map == null)) {
      throw new SQLException("Cannot instantiate a SQLInputImpl " +
          "object with null parameters");
    }
    // assign our local reference to the attribute stream
    attrib = Arrays.copyOf(attributes, attributes.length);
    // init the index point before the head of the stream
    idx = -1;
    // set the map
    this.map = map;
  }


  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as an <code>Object</code> in the Java programming language.
   *
   * @return the next value in the input stream as an <code>Object</code> in the Java programming
   * language
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * further values in the stream
   */
  private Object getNextAttribute() throws SQLException {
    if (++idx >= attrib.length) {
      throw new SQLException("SQLInputImpl exception: Invalid read " +
          "position");
    } else {
      lastValueWasNull = attrib[idx] == null;
      return attrib[idx];
    }
  }

  //================================================================
  // Methods for reading attributes from the stream of SQL data.
  // These methods correspond to the column-accessor methods of
  // java.sql.ResultSet.
  //================================================================

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object as
   * a <code>String</code> in the Java programming language.
   * <p>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code>
   * implementation.
   * <p>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * further values in the stream.
   */
  public String readString() throws SQLException {
    return (String) getNextAttribute();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object as
   * a <code>boolean</code> in the Java programming language.
   * <p>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code>
   * implementation.
   * <p>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * further values in the stream.
   */
  public boolean readBoolean() throws SQLException {
    Boolean attrib = (Boolean) getNextAttribute();
    return (attrib == null) ? false : attrib.booleanValue();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object as
   * a <code>byte</code> in the Java programming language.
   * <p>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code>
   * implementation.
   * <p>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * further values in the stream
   */
  public byte readByte() throws SQLException {
    Byte attrib = (Byte) getNextAttribute();
    return (attrib == null) ? 0 : attrib.byteValue();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as a <code>short</code> in the Java programming language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public short readShort() throws SQLException {
    Short attrib = (Short) getNextAttribute();
    return (attrib == null) ? 0 : attrib.shortValue();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as an <code>int</code> in the Java programming language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public int readInt() throws SQLException {
    Integer attrib = (Integer) getNextAttribute();
    return (attrib == null) ? 0 : attrib.intValue();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as a <code>long</code> in the Java programming language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public long readLong() throws SQLException {
    Long attrib = (Long) getNextAttribute();
    return (attrib == null) ? 0 : attrib.longValue();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as a <code>float</code> in the Java programming language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public float readFloat() throws SQLException {
    Float attrib = (Float) getNextAttribute();
    return (attrib == null) ? 0 : attrib.floatValue();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as a <code>double</code> in the Java programming language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public double readDouble() throws SQLException {
    Double attrib = (Double) getNextAttribute();
    return (attrib == null) ? 0 : attrib.doubleValue();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as a <code>java.math.BigDecimal</code>.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public java.math.BigDecimal readBigDecimal() throws SQLException {
    return (java.math.BigDecimal) getNextAttribute();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as an array of bytes.
   * <p>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public byte[] readBytes() throws SQLException {
    return (byte[]) getNextAttribute();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> as
   * a <code>java.sql.Date</code> object.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type; this responsibility is delegated
   * to the UDT mapping as defined by a <code>SQLData</code> implementation.
   * <P>
   *
   * @return the next attribute in this <code>SQLInputImpl</code> object; if the value is <code>SQL
   * NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position or if there are no
   * more values in the stream
   */
  public java.sql.Date readDate() throws SQLException {
    return (java.sql.Date) getNextAttribute();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object as
   * a <code>java.sql.Time</code> object.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return the attribute; if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public java.sql.Time readTime() throws SQLException {
    return (java.sql.Time) getNextAttribute();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object as
   * a <code>java.sql.Timestamp</code> object.
   *
   * @return the attribute; if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public java.sql.Timestamp readTimestamp() throws SQLException {
    return (java.sql.Timestamp) getNextAttribute();
  }

  /**
   * Retrieves the next attribute in this <code>SQLInputImpl</code> object
   * as a stream of Unicode characters.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return the attribute; if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public java.io.Reader readCharacterStream() throws SQLException {
    return (java.io.Reader) getNextAttribute();
  }

  /**
   * Returns the next attribute in this <code>SQLInputImpl</code> object
   * as a stream of ASCII characters.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return the attribute; if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public java.io.InputStream readAsciiStream() throws SQLException {
    return (java.io.InputStream) getNextAttribute();
  }

  /**
   * Returns the next attribute in this <code>SQLInputImpl</code> object
   * as a stream of uninterpreted bytes.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return the attribute; if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public java.io.InputStream readBinaryStream() throws SQLException {
    return (java.io.InputStream) getNextAttribute();
  }

  //================================================================
  // Methods for reading items of SQL user-defined types from the stream.
  //================================================================

  /**
   * Retrieves the value at the head of this <code>SQLInputImpl</code>
   * object as an <code>Object</code> in the Java programming language.  The
   * actual type of the object returned is determined by the default
   * mapping of SQL types to types in the Java programming language unless
   * there is a custom mapping, in which case the type of the object
   * returned is determined by this stream's type map.
   * <P>
   * The JDBC technology-enabled driver registers a type map with the stream
   * before passing the stream to the application.
   * <P>
   * When the datum at the head of the stream is an SQL <code>NULL</code>,
   * this method returns <code>null</code>.  If the datum is an SQL
   * structured or distinct type with a custom mapping, this method
   * determines the SQL type of the datum at the head of the stream,
   * constructs an object of the appropriate class, and calls the method
   * <code>SQLData.readSQL</code> on that object. The <code>readSQL</code>
   * method then calls the appropriate <code>SQLInputImpl.readXXX</code>
   * methods to retrieve the attribute values from the stream.
   *
   * @return the value at the head of the stream as an <code>Object</code> in the Java programming
   * language; <code>null</code> if the value is SQL <code>NULL</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public Object readObject() throws SQLException {
    Object attrib = getNextAttribute();
    if (attrib instanceof Struct) {
      Struct s = (Struct) attrib;
      // look up the class in the map
      Class<?> c = map.get(s.getSQLTypeName());
      if (c != null) {
        // create new instance of the class
        SQLData obj = null;
        try {
          obj = (SQLData) ReflectUtil.newInstance(c);
        } catch (Exception ex) {
          throw new SQLException("Unable to Instantiate: ", ex);
        }
        // get the attributes from the struct
        Object attribs[] = s.getAttributes(map);
        // create the SQLInput "stream"
        SQLInputImpl sqlInput = new SQLInputImpl(attribs, map);
        // read the values...
        obj.readSQL(sqlInput, s.getSQLTypeName());
        return obj;
      }
    }
    return attrib;
  }

  /**
   * Retrieves the value at the head of this <code>SQLInputImpl</code> object
   * as a <code>Ref</code> object in the Java programming language.
   *
   * @return a <code>Ref</code> object representing the SQL <code>REF</code> value at the head of
   * the stream; if the value is <code>SQL NULL</code> return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public Ref readRef() throws SQLException {
    return (Ref) getNextAttribute();
  }

  /**
   * Retrieves the <code>BLOB</code> value at the head of this
   * <code>SQLInputImpl</code> object as a <code>Blob</code> object
   * in the Java programming language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return a <code>Blob</code> object representing the SQL <code>BLOB</code> value at the head of
   * this stream; if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public Blob readBlob() throws SQLException {
    return (Blob) getNextAttribute();
  }

  /**
   * Retrieves the <code>CLOB</code> value at the head of this
   * <code>SQLInputImpl</code> object as a <code>Clob</code> object
   * in the Java programming language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return a <code>Clob</code> object representing the SQL <code>CLOB</code> value at the head of
   * the stream; if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public Clob readClob() throws SQLException {
    return (Clob) getNextAttribute();
  }

  /**
   * Reads an SQL <code>ARRAY</code> value from the stream and
   * returns it as an <code>Array</code> object in the Java programming
   * language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return an <code>Array</code> object representing the SQL <code>ARRAY</code> value at the head
   * of the stream; * if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public Array readArray() throws SQLException {
    return (Array) getNextAttribute();
  }

  /**
   * Ascertains whether the last value read from this
   * <code>SQLInputImpl</code> object was <code>null</code>.
   *
   * @return <code>true</code> if the SQL value read most recently was <code>null</code>; otherwise,
   * <code>false</code>; by default it will return false
   * @throws SQLException if an error occurs determining the last value read was a <code>null</code>
   * value or not;
   */
  public boolean wasNull() throws SQLException {
    return lastValueWasNull;
  }

  /**
   * Reads an SQL <code>DATALINK</code> value from the stream and
   * returns it as an <code>URL</code> object in the Java programming
   * language.
   * <P>
   * This method does not perform type-safe checking to determine if the
   * returned type is the expected type as this responsibility is delegated
   * to the UDT mapping as implemented by a <code>SQLData</code>
   * implementation.
   *
   * @return an <code>URL</code> object representing the SQL <code>DATALINK</code> value at the head
   * of the stream; * if the value is <code>SQL NULL</code>, return <code>null</code>
   * @throws SQLException if the read position is located at an invalid position; or if there are no
   * further values in the stream.
   */
  public java.net.URL readURL() throws SQLException {
    return (java.net.URL) getNextAttribute();
  }

  //---------------------------- JDBC 4.0 -------------------------

  /**
   * Reads an SQL <code>NCLOB</code> value from the stream and returns it as a
   * <code>Clob</code> object in the Java programming language.
   *
   * @return a <code>NClob</code> object representing data of the SQL <code>NCLOB</code> value at
   * the head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @since 1.6
   */
  public NClob readNClob() throws SQLException {
    return (NClob) getNextAttribute();
  }

  /**
   * Reads the next attribute in the stream and returns it as a <code>String</code>
   * in the Java programming language. It is intended for use when
   * accessing  <code>NCHAR</code>,<code>NVARCHAR</code>
   * and <code>LONGNVARCHAR</code> columns.
   *
   * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code>
   * @throws SQLException if a database access error occurs
   * @since 1.6
   */
  public String readNString() throws SQLException {
    return (String) getNextAttribute();
  }

  /**
   * Reads an SQL <code>XML</code> value from the stream and returns it as a
   * <code>SQLXML</code> object in the Java programming language.
   *
   * @return a <code>SQLXML</code> object representing data of the SQL <code>XML</code> value at the
   * head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @since 1.6
   */
  public SQLXML readSQLXML() throws SQLException {
    return (SQLXML) getNextAttribute();
  }

  /**
   * Reads an SQL <code>ROWID</code> value from the stream and returns it as a
   * <code>RowId</code> object in the Java programming language.
   *
   * @return a <code>RowId</code> object representing data of the SQL <code>ROWID</code> value at
   * the head of the stream; <code>null</code> if the value read is SQL <code>NULL</code>
   * @throws SQLException if a database access error occurs
   * @since 1.6
   */
  public RowId readRowId() throws SQLException {
    return (RowId) getNextAttribute();
  }


}
